Fever & ICU ID

Fever Background

• Regulated by anterior hypothalamus (also brain stem, spinal cord, and sympathetic ganglia)
• Temp is lower in AM and highest in PM
• Mechanism:
  • Interleukin 1 (IL-1), TNF-a, IL-6, and IFN-gamma are released by monocytes and macrophages in response to inflammatory stimuli (or pathogens).
  • These inflammatory mediators stimulate circumventricular organs near the optic chiasm, activing phospholipase A2
    • Phospholipase A2 --> (activates) prostaglantin E2 --> (crosses BB barrier) --> ant. hypothalamus + brain stem. --> FEVER
• Fever is beneficial because:
  • inhibits growth of viruses, bacteria, fungi, parasites.
  • Enhances activity of macrophages, neutrophils, and cell-mediated immune function.
• Fever is harmful because:
  • Increases O2 demand:
    • Cardiac ischemia.
    • COPD exacerbation
    • Elderly with limited mental capacity get confusion.
    • Child seizures. (no proof that reducing the Temp prevents seizure).
• Therefore:
  • Beneficial to lower body temp if heart disease, COPD, elderly, etc..
  • Use prostaglandin E2 synthesis inhibitors:
    • ASA
      • (avoid in children- Reye syndrome - hypoglycemic, fatty liver, encephalopathy, renal changes)
    • NSAIDs
      • Avoid in cardiac - coronary artery vasoconstriction.
    • Acetaminophen

Fever of Unknown Origin

• Definition:

1. Must persist >3weeks.   (otherwise may be viral fever that's impossible to prove)
2. Fever of >38.3°C on several occasions.   (bell curve distribution)
3. No Diagnosis after 3 days of testing.

• Differential:

  • Differential: "The Big Three" Infections Neoplasms Autoimmune Disese "The Little Six" Granulomatous Disease Regional enteritis Familiar Mediterraneal Fever (FMF) Drug Fever Pulmonary emboli Factitions Fever

    Diagnostic Tests: History/physical guides this!!! Go where the money is! CBC + diff Blood smears - Giemsa and Wright stain LFTs ANA, Rheumatoid factor ESR Urinalysis Blood, Urine Cultures PPD skin test Chest and Abdo CT.

    
     
  • "The Big 3"
    • Infections
      • Abscesses (abdo)
      • Osteomyelitis (bone scan)
      • Subacute bacterial endocarditis (blood culture - large volumes, TEE, murmur)
      • Biliary Infections
      • Subacute pyelonephritis
      • Miliary TB
      • Leptospirosis (animal or contaminated soil)
      • Viruses
        • EBV
        • CMV
    • Neoplasms
      • Lymphoma (Hodgkin)
      • Leukemia (aleukemic or preleukemic phase)
      • Hypernephroma (high sedimation rate)
      • Hepatoma
      • Atrial Myxoma
    • Autoimmune Disease
      • Do anti-nuclera and anti-DNA
      • Still's Disease
      • SLE
      • Hypersensitivity angiitis
      • Polymyalgia rheumatica + temporal arteritis
      • Polyarteritis nodosa
      • Mixed connective tissue disease
      • Sybacute thyroiditis
  • "The LIttle Six"
    • Granulomatous disease
    • Regional enteritis
    • Familial Mediterranean Fever (FMF)
    • Drug Fever
      • Antihistamines, barbiturates, dilantin, Hydralazine, Ibuprophen, Isoniazid, nitrofurantoin, penicillins, procainamide, quinidine, Salicylates, Thiouracil, mercaptopurine.
    • Pulmonary Emboli
    • Factitions Fever
      • Mess with mercury thermometers
      • Inject self with feces or saliva (health care worker hx, hiding cyringe)
• Specific History
  • Review of systems
  • Past history of infections and family hx.
  • Epidemiology, animal exposure, insect bites, travel to developing countries or southwest  US or Ohio river valley.
  • Medications
• Specific Exam
  • Skin for embolic lesions
  • Palpate all lymph nodes
  • Complete joint exam
  • Listen for cardic murmurs
  • Abdo exam (liver, spleen, masses/tenderness)

FUO in HIV

• Most common:
  • Mycobacterial infections:   (Mycobacterial blood culture)
    • Mycobacterium tuberculosis
    • M. avium intracellulare
    • Other atypical mycobacteria
  • Other bacterial infections
  • CMV   (CMV quantitative PCR)
  • Pneumocystis
  • Toxoplasmosis
  • Cryptococcus (Cryptococcal serum antigen)
  • Histoplasmosis (hard,  if disseminated - Bone marrow culture)

Fever in ICU (Surgical and Medical)

• Would infection must be excluded
  • Look for signs of infection
  • Immediate postop period:
    • Strep pyogenes --> septic shock and severe bacteremia.
  • Later post-op:
    • S. aureus + nosocomial pathogens (Pseudomonas, Klebsiella, and E.coli)
• CULTURE + GRAM STAIN
• Empiric Abx: cover G+'s and G-'s.
• Specific cases:
  • Intra-abdominal abscess  
    • need CT
  • Intubated (Chest X ray and Blood Gasses)
    • Nasopharynx bacteria --> bronchitis/pneumonia
    • Sputum sample (>10 neutrophils/HPF and single organism on gram stain)
      • CXR and Blood gasses help diff btwn colonization and infection.
  • IV catheters (usually multiple
    • Line sepsis is common.
    • If new fever --> examine all IV and art lines for erythema, warmth, exudate.
    • If new fever + shock --> replace all lines, and maybe culture.
    • Usually: S. aureus, S. epidermidis
      • Use vancomycin (For resistant B-hemolytic strep) + 3rd gen cephalosporin (G-'s)
  • If lots of antibiotics
    • Worry of Candidemia (esp if 2+ site cultures grown Candida)
      • Cover with fluconazole or an echinocandin (caspofungin, anidulafungin, or micafungin) 
      • Blood culture
    • C.difficile colitis
  • Prolongued bladder catheterization
    • Nearly all patients with Foley's develop UTIs in 30days.
    • Urinalysis + Urine culture
  • NG Tubes.
    • Sinusitis + fever
    • Need sinus films + abx.
  • Non-infectious
    • Pulmonary embolus
    • Drug Fever (see above)
    • Undrained blood collections (let them resorb)